Saproxylic beetle assemblages on native and exotic snags in a West African tropical forest

Abstract

The management of dead wood is crucial to the conservation of saproxylic beetles, species dependent on dead wood. This holds for both natural forest and tree plantations. However, the importance of dead wood in tropical forest ecosystems is not yet well understood. The present study investigates saproxylic beetle assemblages of native and exotic standing dead trees (snags). The study was conducted in semi-deciduous protected forest and tree plantations of the Lama Forest Reserve in Benin, West Africa. The snag beetle fauna was sampled for a total of 12 weeks during one year, using trunk window traps. As a control an equal number of live trees was sampled to distinguish saproxylic and non-saproxylic beetles. Mean snag beetle species richness, relative abundance and the number of singletons, species sampled only once, per snag were similar among native and exotic snags. The total number of snag beetle species and beta-diversity of snag beetle assemblages were higher for native than for exotic snags, reflecting high heterogeneity in habitat quality among snags in natural forest. It is concluded that snag beetle assemblages were influenced mainly by the forest system, semi-deciduous forest vs plantations. With regard to dead wood management, retention or creation of snags in semi-deciduous forest, as well as in plantations, can enhance and preserve the diversity of the saproxylic beetle fauna.